US20180154700A1 - Tire - Google Patents
Tire Download PDFInfo
- Publication number
- US20180154700A1 US20180154700A1 US15/575,418 US201615575418A US2018154700A1 US 20180154700 A1 US20180154700 A1 US 20180154700A1 US 201615575418 A US201615575418 A US 201615575418A US 2018154700 A1 US2018154700 A1 US 2018154700A1
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- United States
- Prior art keywords
- tire
- width direction
- land portion
- shoulder land
- shoulder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C11/1204—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe
- B60C11/1218—Three-dimensional shape with regard to depth and extending direction
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C11/1204—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C11/1236—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special arrangements in the tread pattern
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C11/1272—Width of the sipe
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C11/1204—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe
- B60C2011/1209—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe straight at the tread surface
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C11/1204—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe
- B60C2011/1213—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe sinusoidal or zigzag at the tread surface
Definitions
- the present invention relates to a tire which suppresses uneven wear, in particular, a tire which suppresses uneven wear of a shoulder land portion.
- a tire mounted to a passenger vehicle
- various techniques are adopted in order to suppress uneven wear of a tread.
- shoulder uneven wear in which a shoulder land portion is worn more quickly than a center land portion, is known.
- Patent Literature 1 In order to suppress such uneven wear, for example, it is proposed to form a pair of narrow grooves (lateral grooves) extended in a tire width direction, on the shoulder land portion (for example, Patent Literature 1). Specifically, an outward lateral groove opened to a circumferential groove at an outer side in the tire width direction and an inward lateral groove opened to a circumferential groove at an inner side in the tire width direction are formed in the shoulder land portion. According to such a tire, deformation of the shoulder land portion can be suppressed without forming a lateral groove which partitions the shoulder land portion, and thereby the uneven wear (heel and toe wear) of the shoulder land portion is suppressed.
- a vehicle height becomes high especially in a small vehicle (which belongs to the smallest vehicle class in Japan, for example, a displacement of 660 cc or less) by considering the comfortability and the loaded amount of cargos. Further, in minivans which require high comfortability and large loaded amount of cargos, the vehicle height is generally high.
- the vehicle having high vehicle height has a high center of gravity thereof, and therefore a large load is applied especially to the shoulder land portion in turning. Consequently, the shoulder uneven wear is especially apt to arise.
- an object of the present invention is, in consideration of the problem described above, to provide a tire capable of suppressing shoulder uneven wear effectively when the tire is mounted to a vehicle having high vehicle height.
- a feature of the present invention includes that, in a tire having a center land portion (center land portion 20 ) formed in a region including a tire equatorial line (tire equatorial line CL) and a shoulder land portion (for example, shoulder land portion 30 ) formed at an outer side in a tire width direction with respect to the center land portion, a width direction sipe (width direction sipe 100 ) extended in the tire width direction and terminated in the shoulder land portion is formed in the shoulder land portion, and the width direction sipe includes a zigzag portion (zigzag portion 112 ) formed in a zigzag shape in a tire circumferential direction toward at least an inner side of a tire radial direction; a center region (center region Wctr) located at a side of the tire equatorial line in the tire width direction; a shoulder region (inner shoulder region Win) located at a side of a ground contact end of the shoulder land portion in the tire width direction; and an intermediate region (intermediate region Wmid
- the width direction sipe may include a straight portion (straight portion 111 ) formed in a straight shape in the tire radial direction and the tire width direction from a tread surface of the shoulder land portion to a predetermined depth of the width direction sipe.
- a ratio of the straight portion to the zigzag portion in the tire radial direction may become smaller toward the ground contact end of the shoulder land portion.
- the zigzag portion may include a plurality of bent portions (bent portions 112 a, 112 b, 112 c ) in a section along the tire circumferential direction, and the number of the bent portions in the intermediate region may be smaller than the number of the bent portions in at least one of the center region and the shoulder region.
- a width Wsho of the shoulder land portion in the tire width direction and a width Ws of the width direction sipe may be set to fulfill the relation of 0.75 ⁇ (width Ws/width Wsho) ⁇ 0.885.
- the width direction sipe may be formed in each of a shoulder land portion located at an inner side when the tire is mounted to the vehicle and a shoulder land portion located at an outer side when the tire is mounted to the vehicle.
- FIG. 1 is a plane developed view of a part of a tread surface 15 of a tire 10 .
- FIG. 2 is a view illustrating a shape of a width direction sipe 100 formed in a shoulder land portion 30 .
- FIG. 3 is a view illustrating a shape of a width direction sipe 200 formed in a shoulder land portion 30 .
- FIG. 4 is a view illustrating a shape of a width direction sipe 300 formed in a shoulder land portion 40 .
- FIG. 5 is a view illustrating a shape of a width direction sipe 400 formed in a shoulder land portion 40 .
- FIG. 6( a ) is an enlarged plane view of a part of the shoulder land portion 30 .
- FIG. 6( b ) is an enlarged plane view of a part of the shoulder land portion 40 .
- FIG. 7 is a view for describing a state of wear of tires according to a comparative example and examples.
- FIG. 8( a ) is a plane developed view of apart of a shoulder land portion 30 including a width direction sipe 100 A according to a modified example.
- FIG. 8( b ) is a perspective view virtually illustrating a shape of the width direction sipe 100 A.
- FIG. 1 is a plane developed view of a part of a tread surface 15 of a tire 10 according to the present embodiment. As shown in FIG. 1 , a center land portion 20 , a shoulder land portion 30 and a shoulder land portion 40 are formed on the tread surface 15 of the tire 10 .
- the tire 10 is formed as a pneumatic radial tire used by being mounted to a rim wheel (not shown). Here, inert gas such as nitrogen gas may be filled into the tire 10 mounted to the rim wheel.
- the tire 10 can be used in a general passenger vehicle, especially used preferably in a wagon type minicar (small vehicle) or a minivan having a high center of gravity.
- a kind of a vehicle to which the tire 10 can be applied is not limited to such passenger vehicles.
- the center land portion 20 is formed in a region including a tire equatorial line CL passing a center of the tire 10 in the tire width direction and extending in a tire circumferential direction.
- the center land portion 20 is provided with two land portion blocks 21 , 22 separated by a circumferential groove 50 formed at a position of the tire equatorial line CL.
- a plurality of Sipes or narrow grooves may be formed in the land portion blocks 21 , 22 , and therefore the center land portion 20 is not especially limited to a shape shown in FIG. 1 .
- the shoulder land portion 30 is located at an inner side when the tire is mounted to the vehicle.
- the shoulder land portion 30 is formed in a block shape extended in the tire circumferential direction.
- the shoulder land portion 30 is formed at an outer side of a circumferential groove 60 in the tire width direction opposite to the center land portion 20 .
- a width direction sipe 100 and a circumferential direction sipe 200 are formed in the shoulder land portion 30 .
- the shoulder land portion 40 is located at an outer side when the tire is mounted to the vehicle.
- the shoulder land portion 40 is formed in a block shape extended in the tire circumferential direction.
- the shoulder land portion 40 is formed at an outer side of a circumferential groove 70 in the tire width direction opposite to the center land portion 20 .
- a width direction sipe 300 and a circumferential direction sipe 400 are formed in the shoulder land portion 40 .
- the width direction sipe 100 is extended in the tire width direction and terminated in the shoulder land portion 30 .
- the width direction sipe 100 may not be parallel to the tire width direction, and therefore the width direction sipe 100 may be slightly inclined to the tire width direction (for example, 30 degrees or less against the tire width direction).
- the circumferential direction sipe 200 is extended in tire the circumferential direction and terminated in the shoulder land portion 30 .
- the circumferential direction sipe 200 may not be parallel to the tire circumferential direction, and therefore the circumferential direction sipe 200 may be slightly inclined to the tire width direction (for example, 30 degrees or less against the tire width direction).
- the circumferential direction sipe 200 is formed in a region at an inner side of the shoulder land portion 30 in the tire width direction, namely at a position close to the center land portion 20 (the land portion block 21 ). Further, the circumferential direction sipe 200 is formed to overlap with the width direction sipe 100 in the tire width direction.
- the width direction sipe 300 is extended in the tire width direction and terminated in the shoulder land portion 40 .
- the width direction sipe 300 may not be parallel to the tire width direction, and therefore the width direction sipe 300 may be slightly inclined to the tire width direction (for example, 30 degrees or less against the tire width direction).
- the width direction sipes extended in the tire width direction are formed in the shoulder land portion 30 located at the inner side when the tire is mounted to the vehicle and the shoulder land portion 40 located at the outer side when the tire is mounted to the vehicle, respectively.
- the circumferential direction sipe 400 is formed in a region at an inner side of the shoulder land portion 40 in the tire width direction, namely at a position close to the center land portion 20 (the land portion block 22 ). Further, a part of the circumferential direction sipe 400 is formed to overlap with the width direction sipe 300 in the tire width direction.
- a two-dot chain line in FIG. 1 illustrates a pitch of the same tread pattern repeated in the tire circumferential direction.
- a plurality kind of pitches (pitch variation) in the tire circumferential direction is set in the tire 10 .
- each configuration of the shoulder land portion 30 and the shoulder land portion 40 is described. Specifically, each shape of the width direction sipe 100 and the circumferential direction sipe 200 formed in the shoulder land portion 30 and each shape of the width direction sipe 300 and the circumferential direction sipe 400 formed in the shoulder land portion 40 are described.
- FIG. 2 illustrates the shape of the width direction sipe 100 formed in the shoulder land portion 30 . Specifically, FIG. 2 illustrates a front shape of the width direction sipe 100 along the tire width direction, and a side shape of the width direction sipe 100 .
- the width direction sipe 100 is provided with a straight portion 111 and a zigzag portion 112 .
- the straight portion 111 is formed in a straight shape in the tire radial direction and the tire width direction, namely a flat plate shape.
- the straight portion 111 is formed from the tread surface 15 of the shoulder land portion 30 to a predetermined depth of the width direction sipe 100 .
- a ratio of the straight portion 111 to the zigzag portion 112 in the tire radial direction, namely a depth direction of the width direction sipe 100 is not especially limited, however as shown in FIG. 2 , it is preferable that a length (depth) of the zigzag portion 112 is longer than a length of the straight portion 111 . Further, a depth of the width direction sipe 100 is preferably set in a range between 4 mm and 10 mm.
- the ratio of the straight portion 111 to the zigzag portion 112 becomes smaller toward a ground contact end Se of the shoulder land portion 30 . This is because the tread surface 15 of the shoulder land portion 30 is inclined to be closer to the inner side of the tire radial direction toward the outer side of the tire width direction and therefore a depth of the straight portion 111 becomes smaller toward the ground contact end Se.
- a position of the ground contact end Se is defined by the tire 10 mounted to a wheel rim (normal rim wheel) having a standard size defined in Year Book of Japan Automobile Tyre Manufacturers Association (JATMA) in a state in which measurement conditions (mounting to an applied rim, setting of defined inner pressure, setting temperature or the like) defined in JATMA are fulfilled.
- JATMA Year Book of Japan Automobile Tyre Manufacturers Association
- other standard TRA, ETRTO
- the zigzag portion 112 is formed at an inner side of the straight portion 111 in the tire radial direction. That is, the zigzag portion 112 is formed at a position deeper than the straight portion 111 in the depth direction of the width direction sipe 100 .
- the zigzag portion 112 is provided with a plurality of bent portions, specifically bent portions 112 a to 112 c, in a section along the tire circumferential direction. More specifically, the bent portion 112 a, the bent portion 112 b and the bent portion 112 c are formed from a side of the treat surface 15 along the tire radial direction (the depth direction of the width direction sipe 100 ). A bottom portion 113 is located at an inner side of the bent portion 112 c in the tire radial direction.
- Each of the angles of the bent portions 112 a, 112 b, 112 c is set to be approximately 90 degrees in a section along the tire circumferential direction.
- the angle may be set to be more than 90 degrees, however around 90 degrees are preferable from a viewpoint of suppressing falling of the shoulder land portion 30 effectively.
- the zigzag portion 112 may be formed in a zigzag shape in the tire circumferential direction at least toward the inner side of the tire radial direction. Accordingly, as described below (see other embodiments), the zigzag portion 112 may be formed as a so-called three-dimensional sipe formed in a zigzag shape in the tire circumferential direction toward the tire width direction as well as the tire radial direction.
- the width direction sipe 100 is described by separating into a center region Wctr, an intermediate region Wmid, and an inner shoulder region Win.
- the center region Wctr is located at a side of the tire equatorial line CL.
- the inner shoulder region Win is located at a side of the ground contact end Se of the shoulder land portion 30 .
- the intermediate region Wmid is located between the center region Wctr and the inner shoulder region Win.
- the zigzag portion 112 in the center region Wctr and the zigzag portion 112 in the inner shoulder region Win are longer than the zigzag portion 112 in the intermediate region Wmid in the tire radial direction.
- the maximum groove depth of each of the width direction sipes 100 in the center region Wctr and the inner shoulder region Win is deeper than the maximum groove depth of the width direction sipe 100 in the intermediate region Wmid.
- a deep groove portion 120 ctr is formed in the center region Wctr, and a deep groove portion 120 in is formed in the inner shoulder region Win.
- the number of the bent portions in the intermediate region Wmid is smaller than the number of the bent portions in each of the center region Wctr and the inner shoulder region Win. Specifically, the number of the bent portions in each of the center region Wctr and the inner shoulder region Win is three (the bent portions 112 a, 112 b, 112 c ), while the number of the bent portions in the intermediate region Wmid is two (the bent portions 112 a, 112 b ).
- the number of bent portions in each of the center region Wctr and the inner shoulder region Win is not necessarily set to be larger than the number of the bent portions in the intermediate region Wmid. That is, the number of the bent portions in the intermediate region Wmid may be set to be smaller than the number of the bent portions in either of the center region Wctr and the inner shoulder region Win.
- the number of “peaks” caused by the bent portions from the tread surface 15 to the bottom portion 113 in each of the center region Wctr and the inner shoulder region Win is set to 3.5 including an inclined portion from the bent portion 112 c to the bottom portion 113 .
- the number of “peaks” caused by the bent portions in the intermediate region Wmid is set to 3.0.
- a ratio of each of the center region Wctr and the inner shoulder region Win to a width Ws, which is a whole width of the width direction sipe 100 is preferably set to fulfill the following each relation.
- (center region Wctr/width Ws) in the formula 1 is 0.47
- (inner shoulder region Win/width Ws) in the formula 2 is 0.22. Further, in a case in which each value thereof is beyond the range of each of the formulas 1 and 2, a suppression effect of the uneven wear of the shoulder land portion 30 is deteriorated.
- FIG. 3 illustrates the shape of the circumferential direction sipe 200 formed in the shoulder land portion 30 .
- FIG. 3 illustrates a side shape of the circumferential direction sipe 200 seen from a F 3 -F 3 direction shown in FIG. 1 .
- the circumferential direction sipe 200 is formed in a simply flat plate shape.
- the circumferential direction sipe 200 is provided with a side wall 210 , and a bottom portion 211 continued to the side wall 210 . It is preferable that a groove depth of the circumferential direction sipe 200 from the tread surface 15 to the bottom portion 211 is substantially the same as a groove depth of the width direction sipe 100 in the intermediate region Wmid or is smaller than the groove depth of the width direction sipe 100 in the intermediate region Wmid.
- FIG. 4 illustrates the shape of the width direction sipe 300 formed in the shoulder land portion 40 .
- FIG. 4 illustrates a front shape of the width direction sipe 300 along the tire width direction, and a side shape of the width direction sipe 300 .
- the width direction sipe 300 is formed symmetrically to the width direction sipe 100 , and therefore the description of a similar part to the width direction sipe 100 is omitted for convenience.
- the width direction sipe 300 is provided with a straight portion 311 and a zigzag portion 312 .
- the straight portion 311 and the zigzag portion 312 have shapes similar to the straight portion 111 and the zigzag portion 112 , respectively. Similar to the width direction sipe 100 , it is preferable that a length (depth) of the zigzag portion 312 is longer than a length of the straight portion 311 . A ratio of the straight portion 311 to the zigzag portion 312 in a depth direction of the width direction sipe 300 becomes smaller toward the ground contact end Se of the shoulder land portion 40 .
- a bent portion 312 a, a bent portion 312 b and a bent portion 312 c are formed from the side of the tread surface 15 along the tire radial direction (the depth direction of the width direction sipe 300 ).
- a bottom portion 313 is located at an inner side of the bent portion 312 c in the tire radial direction.
- an outer shoulder region Wout is located at a side of the ground contact end Se of the shoulder land portion 40 .
- An intermediate region Wmid is located between a center region Wctr and the outer shoulder region Wout.
- the zigzag portion 312 in the center region Wctr and the zigzag portion 312 in the outer shoulder portion Wout are longer than the zigzag portion 312 in the intermediate region Wmid in the tire radial direction.
- the maximum groove depth of the width direction sipes 300 in each of the center region Wctr and the outer shoulder region Wout is deeper than the maximum groove depth of the width direction sipe 300 in the intermediate region Wmid.
- a deep groove portion 320 ctr is formed in the center region Wctr, and a deep groove portion 320 out is formed in the outer shoulder region Wout.
- each of the bent portions 312 a, 312 b, 312 c formed in the zigzag portion 312 is similar to that in the zigzag portion 112 of the width direction sipe 100 .
- a ratio of each of the center region Wctr and the outer shoulder region Wout to the width Ws, which is a whole width of the width direction sipe 300 is preferably set to fulfill the each relation represented by the formulas 1 and 2.
- the formula 2 is replaced as below.
- (outer shoulder region Wout/width Ws) in the formula 2′ is 0.22. Further, in a case in which the value thereof is beyond the range of the formula 2′, the suppression effect of the uneven wear of the shoulder land portion 30 is deteriorated.
- FIG. 5 illustrates the shape of the circumferential direction sipe 400 formed in the shoulder land portion 40 .
- FIG. 5 illustrates a side shape of the circumferential direction sipe 400 seen from a F 5 -F 5 direction shown in FIG. 1 .
- the circumferential direction sipe 400 is formed in a simply flat plate shape.
- the circumferential direction sipe 400 is provided with a side wall 410 , and a bottom portion 411 continued to the side wall 210 . It is preferable that a groove depth of the circumferential direction sipe 400 from the tread surface 15 to the bottom portion 411 is set in a range between the groove depth of the width direction sipe 100 in the intermediate region Wmid and the groove depth of the width direction sipe 100 in the center region Wctr or the outer shoulder land portion Wout.
- FIGS. 6( a ) and 6( b ) are enlarged plane views of a part of the shoulder land portion 30 and a part of the shoulder land portion 40 , respectively.
- a width Wsho of the shoulder land portion 30 and the width Ws of the width direction sipe 100 in the tire width direction fulfill the following relation.
- width Ws/width Wsho defined by the width Ws of the width direction sipe 100 and the width Wsho of the shoulder land portion 30 is 0.818. Further, in a case in which the value thereof is beyond the range of the formula 3, the suppression effect of the uneven wear of the shoulder land portion 30 is deteriorated.
- a width Wsho of the shoulder land portion 40 and a width Ws of the width direction sipe 300 in the tire width direction fulfill a similar relation.
- the width Wsho and the width Ws fulfill the following relation.
- width Ws/width Wsho defined by the width Ws of the width direction sipe 300 and the width Wsho of the shoulder land portion 40 is 0.869.
- the width direction sipe 100 is extended from a position of the ground contact end Se of the shoulder land portion 30 toward the inner side of the tire width direction.
- the width direction sipe 300 is extended from a position of the ground contact end Se of the shoulder land portion 40 toward the inner side of the tire width direction.
- Table 1 shows a condition of a wear test of the tire 10 (examples 1 to 4) in which the width direction sipes 100 , 300 described above are formed and a tire (comparative example) in which the width direction sipe is not formed and a result thereof.
- Example 2 Example 3
- Example 4 Tire size 155/65R14 155/65R14 155/65R14 155/65R14 155/65R14 155/65R14 155/65R14 With direction sipe No Yes Yes Yes Yes Index of wear life 100 108 105 107 101 center region Wctr/width N.A. 0.47 0.34 0.48 0.53 Ws (formula 1) inner shoulder region N.A. 0.22 0.20 0.24 0.27 Win/width Ws (formula 2) and outer shoulder region Wout/ width Ws (formula 2′) width Ws/width Wsho N.A. 0.818 0.772 0.865 0.899 (outer side) (formula 3) width Ws/width Wsho N.A. 0.869 0.82 0.88 0.912 (inner side) (formula 3′)
- each index of the wear life of the tires according to the examples 1 to 4 is improved to 101 or more.
- index of wear life denotes that a wear amount of a tread portion after an evaluation target tire travels for a predetermined distance by means of a drum test, is indexed against that of the comparative example as a reference (the wear amount is smaller as the value is larger).
- an input frequency distribution in an actual use environment to the tire mounted to a front axle is reproduced. Further, after the tire travels for the predetermined distance, the tire rotation of the right tire and the left tire on the front axle is performed. Further, each wear amount is measured based on a depth of the retaining groove (including the sipe) formed in each of the shoulder land portion located at the inner side when the tire is mounted to the vehicle and the shoulder land portion located at the outer side when the tire is mounted to the vehicle.
- each value thereof is beyond the each range represented by the formulas 1, 2, 2′, 3, and 3′ (underlines are applied in Table 1).
- FIG. 7 is a view for describing a state of wear of the tires according to the comparative example and the example 1 shown in Table 1. Specifically, FIG. 7 shows a graph of each remaining amount of the groove of the shoulder land portion at the outer side, the center land portion, and the shoulder land portion at the inner side when the tire is mounted to the front axle of a vehicle (minicar). Further, as described above, after the evaluation target tire travels for the predetermined distance, the tire rotation of the right tire and the left tire is performed.
- the tire according to the example 1 has less wear difference between the shoulder land portions at the both sides and the center land portion, and therefore the shoulder land portions and the center land portion are worn uniformly.
- the tire according to the comparative example has large wear difference between the shoulder land portions at the both sides and the center land portion, and therefore the shoulder land portions are worn more quickly than the center land portion.
- the tire is apt to reach a use limit earlier due to the wear of the shoulder land portion in spite of the sufficient remaining amount of the groove of the center land portion.
- the tire according to the example 1 has less wear difference between the shoulder land portions at the both sides and the center portion, and therefore travel distance of the tire until the use limit thereof due to the wear can be extended.
- the zigzag portion 112 in the center region Wctr and the zigzag portion 112 in the inner shoulder region Win of the width direction sipe 100 are longer than the zigzag portion 112 in the intermediate region Wmid in the tire radial direction.
- the shoulder land portions 30 separated by the zigzag portion 112 support one another, and therefore block rigidity of the inner shoulder region Win and the center region Wctr is improved.
- the block rigidity is improved, deformation of each of the inner shoulder region Win and the center region Wctr of the shoulder land portion 30 is suppressed, and therefore ground contact pressure of each of the inner shoulder region Win and the center region Wctr is decreased.
- each ground contact pressure of the shoulder land portions (parts adjacent to the circumferential groove) at a side of the ground contact end and a side of the center land portion becomes higher due to an influence of wheel alignment (especially, a camber angle) of the vehicle.
- minicars having high vehicle height by considering high comfortability and large loaded amount of cargos or the minivans generally having high vehicle height are apt to be high in the center of gravity.
- a roll amount of the vehicle becomes especially large in turning, and therefore a high load is applied to the shoulder land portion and the ground contact pressure becomes high.
- each ground contact pressure of the inner shoulder region Win and the center region Wctr can be decreased and the falling of the shoulder land portion 30 can be prevented by the improvement of the block rigidity.
- the shoulder uneven wear specifically the wear of the inner shoulder region Win and the center region Wctr proceeding more quickly than the wear of the intermediate region Wmid, is suppressed. Further, the falling of the shoulder land portion 30 can be also prevented, and therefore heel and toe wear of the shoulder land portion 30 is also suppressed.
- the width direction sipe 100 is provided with the straight portion 111 from the tread surface of the shoulder land portion 30 to the predetermined depth of the width direction sipe 100 .
- the rigidity of the shoulder land portion 30 close to the tread surface 15 is not excessively increased, and therefore the shoulder uneven wear can be suppressed while ensuring comfortability and suppressing pattern noise.
- the ratio of the straight portion 111 to the zigzag portion 112 in the tire radial direction becomes smaller toward the ground contact end Se of the shoulder land portion 30 .
- the rigidity of the shoulder land portion 30 becomes relatively larger toward the ground contact end Se. That is, since the ground contact pressure of the shoulder land portion 30 becomes lower toward the ground contact end Se, the uneven wear near the ground contact end Se can be suppressed effectively.
- the number of the bent portions in the intermediate region Wmid is smaller than the number of the bent portions in each of the center region Wctr and the shoulder region Win.
- the block rigidity of each of the inner shoulder region Win and the center region Wctr is improved much more than that of the intermediate region Wmid, and as described above, each ground contact pressure of the inner shoulder region Win and the center region Wctr is decreased. Accordingly, the shoulder uneven wear, specifically the wear of the inner shoulder region Win and the center region Wctr proceeding more quickly than the wear of the intermediate region Wmid, is suppressed.
- the width Wsho of the shoulder land portion 30 and the width Ws of the width direction sipe 100 in the tire width direction fulfill the relation of 0.75 ⁇ (width Ws/width Wsho) ⁇ 0.885. Since the zigzag portion 112 is formed in the width direction sipe 100 such that the zigzag portion 112 in each of the inner shoulder region Win and the center region Wctr is longer than the zigzag portion 112 in the intermediate region Wmid, and since such a width direction sipe 100 is formed in the most part of the width of the shoulder land portion 30 , the uneven wear of the shoulder land portion 30 close to the ground contact end Se and the shoulder land portion 30 close to the center land portion 20 can be suppressed effectively.
- the width direction sipe 100 is formed in the shoulder land portion 30 located at the inner side when the tire is mounted to the vehicle, and the width direction sipe 300 is formed in the shoulder land portion 40 located at the outer side when the tire is mounted to the vehicle.
- width direction sipe 100 ( 300 ) formed in the tire 10 may be modified as described below.
- FIGS. 8( a ) and 8( b ) are a plane developed view of a part of a shoulder land portion 30 including a width direction sipe 100 A according to a modified example of the present invention and a perspective view virtually illustrating a shape of the width direction sipe 100 A, respectively.
- the width direction sipe 100 A is formed in a zigzag shape in the tire radial direction, the tire circumferential direction and the tire width direction, namely a three-dimensional sipe.
- Such a width direction sipe 100 A and the circumferential direction sipe 200 maybe formed in the shoulder land portion 30 .
- the width direction sipe 100 A is formed, similar to the width direction sipe 100 , such that a length of the width direction sipe 100 A along the tire radial direction (depth) in each of a shoulder region and a center region is longer than a length the width direction sipe 100 A along the tire radial direction (depth) in an intermediate region.
- a three-dimensional sipe which is similar to the width direction sipe 100 A, may be formed in the shoulder land portion 40 .
- the width direction sipe is formed in each of the shoulder land portion 30 and the shoulder land portion 40 , however the width direction sipe may be formed in either of the shoulder land portions.
- a plurality of the bent portions is formed in the zigzag portion 112 , however the zigzag portion 112 may be formed in a shape in which a wave-like curve is repeated, instead of a definitely bent shape as long as the shoulder portions 30 separated by the zigzag portion 112 support one another.
- the tire capable of suppressing shoulder uneven wear effectively even if the tire is mounted to a vehicle having high vehicle height, can be provided.
Abstract
Description
- The present invention relates to a tire which suppresses uneven wear, in particular, a tire which suppresses uneven wear of a shoulder land portion.
- Conventionally, in a pneumatic tire (hereinafter, referred to as a tire) mounted to a passenger vehicle, various techniques are adopted in order to suppress uneven wear of a tread. As one aspect of the uneven wear of the tread, shoulder uneven wear in which a shoulder land portion is worn more quickly than a center land portion, is known.
- In order to suppress such uneven wear, for example, it is proposed to form a pair of narrow grooves (lateral grooves) extended in a tire width direction, on the shoulder land portion (for example, Patent Literature 1). Specifically, an outward lateral groove opened to a circumferential groove at an outer side in the tire width direction and an inward lateral groove opened to a circumferential groove at an inner side in the tire width direction are formed in the shoulder land portion. According to such a tire, deformation of the shoulder land portion can be suppressed without forming a lateral groove which partitions the shoulder land portion, and thereby the uneven wear (heel and toe wear) of the shoulder land portion is suppressed.
-
- [PTL 1] Japanese Unexamined Patent Application Publication No. 2007-261296 (pages 4 to 6 and FIG. 1)
- In recent years, there is a tendency that a vehicle height becomes high especially in a small vehicle (which belongs to the smallest vehicle class in Japan, for example, a displacement of 660 cc or less) by considering the comfortability and the loaded amount of cargos. Further, in minivans which require high comfortability and large loaded amount of cargos, the vehicle height is generally high.
- The vehicle having high vehicle height has a high center of gravity thereof, and therefore a large load is applied especially to the shoulder land portion in turning. Consequently, the shoulder uneven wear is especially apt to arise.
- Accordingly, an object of the present invention is, in consideration of the problem described above, to provide a tire capable of suppressing shoulder uneven wear effectively when the tire is mounted to a vehicle having high vehicle height.
- A feature of the present invention includes that, in a tire having a center land portion (center land portion 20) formed in a region including a tire equatorial line (tire equatorial line CL) and a shoulder land portion (for example, shoulder land portion 30) formed at an outer side in a tire width direction with respect to the center land portion, a width direction sipe (width direction sipe 100) extended in the tire width direction and terminated in the shoulder land portion is formed in the shoulder land portion, and the width direction sipe includes a zigzag portion (zigzag portion 112) formed in a zigzag shape in a tire circumferential direction toward at least an inner side of a tire radial direction; a center region (center region Wctr) located at a side of the tire equatorial line in the tire width direction; a shoulder region (inner shoulder region Win) located at a side of a ground contact end of the shoulder land portion in the tire width direction; and an intermediate region (intermediate region Wmid) located between the center region and the shoulder region in the tire width direction, and the zigzag portion in the center region and the zigzag portion in the shoulder region are longer than the zigzag portion in the intermediate portion in the tire radial direction.
- In the feature of the present invention, the width direction sipe may include a straight portion (straight portion 111) formed in a straight shape in the tire radial direction and the tire width direction from a tread surface of the shoulder land portion to a predetermined depth of the width direction sipe.
- In the feature of the present invention, a ratio of the straight portion to the zigzag portion in the tire radial direction may become smaller toward the ground contact end of the shoulder land portion.
- In the feature of the present invention, the zigzag portion may include a plurality of bent portions (
bent portions - In the feature of the present invention, a width Wsho of the shoulder land portion in the tire width direction and a width Ws of the width direction sipe may be set to fulfill the relation of 0.75≤(width Ws/width Wsho)≤0.885.
- In the feature of the present invention, the width direction sipe may be formed in each of a shoulder land portion located at an inner side when the tire is mounted to the vehicle and a shoulder land portion located at an outer side when the tire is mounted to the vehicle.
-
FIG. 1 is a plane developed view of a part of atread surface 15 of atire 10. -
FIG. 2 is a view illustrating a shape of awidth direction sipe 100 formed in ashoulder land portion 30. -
FIG. 3 is a view illustrating a shape of awidth direction sipe 200 formed in ashoulder land portion 30. -
FIG. 4 is a view illustrating a shape of awidth direction sipe 300 formed in ashoulder land portion 40. -
FIG. 5 is a view illustrating a shape of awidth direction sipe 400 formed in ashoulder land portion 40. -
FIG. 6(a) is an enlarged plane view of a part of theshoulder land portion 30.FIG. 6(b) is an enlarged plane view of a part of theshoulder land portion 40. -
FIG. 7 is a view for describing a state of wear of tires according to a comparative example and examples. -
FIG. 8(a) is a plane developed view of apart of ashoulder land portion 30 including awidth direction sipe 100A according to a modified example.FIG. 8(b) is a perspective view virtually illustrating a shape of thewidth direction sipe 100A. - Next, embodiments of a tire according to the present invention are described with reference to the drawings. In the following description of the drawings, the same or similar reference numerals are assigned to the same or similar parts.
-
FIG. 1 is a plane developed view of a part of atread surface 15 of atire 10 according to the present embodiment. As shown inFIG. 1 , acenter land portion 20, ashoulder land portion 30 and ashoulder land portion 40 are formed on thetread surface 15 of thetire 10. Thetire 10 is formed as a pneumatic radial tire used by being mounted to a rim wheel (not shown). Here, inert gas such as nitrogen gas may be filled into thetire 10 mounted to the rim wheel. - The
tire 10 can be used in a general passenger vehicle, especially used preferably in a wagon type minicar (small vehicle) or a minivan having a high center of gravity. However, a kind of a vehicle to which thetire 10 can be applied is not limited to such passenger vehicles. - The
center land portion 20 is formed in a region including a tire equatorial line CL passing a center of thetire 10 in the tire width direction and extending in a tire circumferential direction. In the present embodiment, thecenter land portion 20 is provided with twoland portion blocks circumferential groove 50 formed at a position of the tire equatorial line CL. - Here, as shown in
FIG. 1 , a plurality of Sipes or narrow grooves may be formed in theland portion blocks center land portion 20 is not especially limited to a shape shown inFIG. 1 . - The
shoulder land portion 30 is located at an inner side when the tire is mounted to the vehicle. Theshoulder land portion 30 is formed in a block shape extended in the tire circumferential direction. Theshoulder land portion 30 is formed at an outer side of acircumferential groove 60 in the tire width direction opposite to thecenter land portion 20. Awidth direction sipe 100 and acircumferential direction sipe 200 are formed in theshoulder land portion 30. - The
shoulder land portion 40 is located at an outer side when the tire is mounted to the vehicle. Theshoulder land portion 40 is formed in a block shape extended in the tire circumferential direction. Theshoulder land portion 40 is formed at an outer side of acircumferential groove 70 in the tire width direction opposite to thecenter land portion 20. Awidth direction sipe 300 and acircumferential direction sipe 400 are formed in theshoulder land portion 40. - The
width direction sipe 100 is extended in the tire width direction and terminated in theshoulder land portion 30. Here, as shown inFIG. 1 , thewidth direction sipe 100 may not be parallel to the tire width direction, and therefore thewidth direction sipe 100 may be slightly inclined to the tire width direction (for example, 30 degrees or less against the tire width direction). - The
circumferential direction sipe 200 is extended in tire the circumferential direction and terminated in theshoulder land portion 30. Here, thecircumferential direction sipe 200 may not be parallel to the tire circumferential direction, and therefore thecircumferential direction sipe 200 may be slightly inclined to the tire width direction (for example, 30 degrees or less against the tire width direction). - The
circumferential direction sipe 200 is formed in a region at an inner side of theshoulder land portion 30 in the tire width direction, namely at a position close to the center land portion 20 (the land portion block 21). Further, thecircumferential direction sipe 200 is formed to overlap with thewidth direction sipe 100 in the tire width direction. - The
width direction sipe 300 is extended in the tire width direction and terminated in theshoulder land portion 40. Here, as shown inFIG. 1 , thewidth direction sipe 300 may not be parallel to the tire width direction, and therefore thewidth direction sipe 300 may be slightly inclined to the tire width direction (for example, 30 degrees or less against the tire width direction). - In this way, in the present embodiment, the width direction sipes extended in the tire width direction are formed in the
shoulder land portion 30 located at the inner side when the tire is mounted to the vehicle and theshoulder land portion 40 located at the outer side when the tire is mounted to the vehicle, respectively. - The
circumferential direction sipe 400 is formed in a region at an inner side of theshoulder land portion 40 in the tire width direction, namely at a position close to the center land portion 20 (the land portion block 22). Further, a part of thecircumferential direction sipe 400 is formed to overlap with thewidth direction sipe 300 in the tire width direction. - Further, a two-dot chain line in
FIG. 1 illustrates a pitch of the same tread pattern repeated in the tire circumferential direction. Generally, a plurality kind of pitches (pitch variation) in the tire circumferential direction is set in thetire 10. - Next, each configuration of the
shoulder land portion 30 and theshoulder land portion 40 is described. Specifically, each shape of thewidth direction sipe 100 and thecircumferential direction sipe 200 formed in theshoulder land portion 30 and each shape of thewidth direction sipe 300 and thecircumferential direction sipe 400 formed in theshoulder land portion 40 are described. -
FIG. 2 illustrates the shape of thewidth direction sipe 100 formed in theshoulder land portion 30. Specifically,FIG. 2 illustrates a front shape of thewidth direction sipe 100 along the tire width direction, and a side shape of thewidth direction sipe 100. - As shown in
FIG. 2 , thewidth direction sipe 100 is provided with astraight portion 111 and azigzag portion 112. - The
straight portion 111 is formed in a straight shape in the tire radial direction and the tire width direction, namely a flat plate shape. Thestraight portion 111 is formed from thetread surface 15 of theshoulder land portion 30 to a predetermined depth of thewidth direction sipe 100. - A ratio of the
straight portion 111 to thezigzag portion 112 in the tire radial direction, namely a depth direction of thewidth direction sipe 100, is not especially limited, however as shown inFIG. 2 , it is preferable that a length (depth) of thezigzag portion 112 is longer than a length of thestraight portion 111. Further, a depth of thewidth direction sipe 100 is preferably set in a range between 4 mm and 10 mm. - The ratio of the
straight portion 111 to thezigzag portion 112 becomes smaller toward a ground contact end Se of theshoulder land portion 30. This is because thetread surface 15 of theshoulder land portion 30 is inclined to be closer to the inner side of the tire radial direction toward the outer side of the tire width direction and therefore a depth of thestraight portion 111 becomes smaller toward the ground contact end Se. - A position of the ground contact end Se is defined by the
tire 10 mounted to a wheel rim (normal rim wheel) having a standard size defined in Year Book of Japan Automobile Tyre Manufacturers Association (JATMA) in a state in which measurement conditions (mounting to an applied rim, setting of defined inner pressure, setting temperature or the like) defined in JATMA are fulfilled. Here, other standard (TRA, ETRTO) may be adopted instead of JATMA. - The
zigzag portion 112 is formed at an inner side of thestraight portion 111 in the tire radial direction. That is, thezigzag portion 112 is formed at a position deeper than thestraight portion 111 in the depth direction of thewidth direction sipe 100. - The
zigzag portion 112 is provided with a plurality of bent portions, specificallybent portions 112 a to 112 c, in a section along the tire circumferential direction. More specifically, thebent portion 112 a, thebent portion 112 b and thebent portion 112 c are formed from a side of thetreat surface 15 along the tire radial direction (the depth direction of the width direction sipe 100). Abottom portion 113 is located at an inner side of thebent portion 112 c in the tire radial direction. - Each of the angles of the
bent portions shoulder land portion 30 effectively. - The
zigzag portion 112 may be formed in a zigzag shape in the tire circumferential direction at least toward the inner side of the tire radial direction. Accordingly, as described below (see other embodiments), thezigzag portion 112 may be formed as a so-called three-dimensional sipe formed in a zigzag shape in the tire circumferential direction toward the tire width direction as well as the tire radial direction. - Here, as shown in
FIG. 2 , thewidth direction sipe 100 is described by separating into a center region Wctr, an intermediate region Wmid, and an inner shoulder region Win. - The center region Wctr is located at a side of the tire equatorial line CL. The inner shoulder region Win is located at a side of the ground contact end Se of the
shoulder land portion 30. The intermediate region Wmid is located between the center region Wctr and the inner shoulder region Win. - The
zigzag portion 112 in the center region Wctr and thezigzag portion 112 in the inner shoulder region Win are longer than thezigzag portion 112 in the intermediate region Wmid in the tire radial direction. - That is, the maximum groove depth of each of the
width direction sipes 100 in the center region Wctr and the inner shoulder region Win is deeper than the maximum groove depth of thewidth direction sipe 100 in the intermediate region Wmid. Thus, a deep groove portion 120ctr is formed in the center region Wctr, and a deep groove portion 120in is formed in the inner shoulder region Win. - The number of the bent portions in the intermediate region Wmid is smaller than the number of the bent portions in each of the center region Wctr and the inner shoulder region Win. Specifically, the number of the bent portions in each of the center region Wctr and the inner shoulder region Win is three (the
bent portions bent portions - Further, the number of bent portions in each of the center region Wctr and the inner shoulder region Win is not necessarily set to be larger than the number of the bent portions in the intermediate region Wmid. That is, the number of the bent portions in the intermediate region Wmid may be set to be smaller than the number of the bent portions in either of the center region Wctr and the inner shoulder region Win.
- In the present embodiment, the number of “peaks” caused by the bent portions from the
tread surface 15 to thebottom portion 113 in each of the center region Wctr and the inner shoulder region Win is set to 3.5 including an inclined portion from thebent portion 112 c to thebottom portion 113. On the other hand, the number of “peaks” caused by the bent portions in the intermediate region Wmid is set to 3.0. - Further, a ratio of each of the center region Wctr and the inner shoulder region Win to a width Ws, which is a whole width of the
width direction sipe 100, is preferably set to fulfill the following each relation. -
0.34<(center region Wctr/width Ws)<0.49 (formula 1) -
0.19<(inner shoulder region Win/width Ws)<0.25 (formula 2) - Here, in the present embodiment, (center region Wctr/width Ws) in the
formula 1 is 0.47, and (inner shoulder region Win/width Ws) in the formula 2 is 0.22. Further, in a case in which each value thereof is beyond the range of each of theformulas 1 and 2, a suppression effect of the uneven wear of theshoulder land portion 30 is deteriorated. -
FIG. 3 illustrates the shape of thecircumferential direction sipe 200 formed in theshoulder land portion 30. Specifically,FIG. 3 illustrates a side shape of thecircumferential direction sipe 200 seen from a F3-F3 direction shown inFIG. 1 . As shown inFIG. 3 , thecircumferential direction sipe 200 is formed in a simply flat plate shape. - The
circumferential direction sipe 200 is provided with aside wall 210, and abottom portion 211 continued to theside wall 210. It is preferable that a groove depth of thecircumferential direction sipe 200 from thetread surface 15 to thebottom portion 211 is substantially the same as a groove depth of thewidth direction sipe 100 in the intermediate region Wmid or is smaller than the groove depth of thewidth direction sipe 100 in the intermediate region Wmid. -
FIG. 4 illustrates the shape of thewidth direction sipe 300 formed in theshoulder land portion 40. Specifically,FIG. 4 illustrates a front shape of thewidth direction sipe 300 along the tire width direction, and a side shape of thewidth direction sipe 300. Here, thewidth direction sipe 300 is formed symmetrically to thewidth direction sipe 100, and therefore the description of a similar part to thewidth direction sipe 100 is omitted for convenience. - As shown in
FIG. 4 , thewidth direction sipe 300 is provided with astraight portion 311 and azigzag portion 312. - The
straight portion 311 and thezigzag portion 312 have shapes similar to thestraight portion 111 and thezigzag portion 112, respectively. Similar to thewidth direction sipe 100, it is preferable that a length (depth) of thezigzag portion 312 is longer than a length of thestraight portion 311. A ratio of thestraight portion 311 to thezigzag portion 312 in a depth direction of thewidth direction sipe 300 becomes smaller toward the ground contact end Se of theshoulder land portion 40. - In the
zigzag portion 312, similar to thewidth direction sipe 100, abent portion 312 a, abent portion 312 b and abent portion 312 c are formed from the side of thetread surface 15 along the tire radial direction (the depth direction of the width direction sipe 300). Abottom portion 313 is located at an inner side of thebent portion 312 c in the tire radial direction. - In the
width direction sipe 300, an outer shoulder region Wout is located at a side of the ground contact end Se of theshoulder land portion 40. An intermediate region Wmid is located between a center region Wctr and the outer shoulder region Wout. - The
zigzag portion 312 in the center region Wctr and thezigzag portion 312 in the outer shoulder portion Wout are longer than thezigzag portion 312 in the intermediate region Wmid in the tire radial direction. - That is, the maximum groove depth of the
width direction sipes 300 in each of the center region Wctr and the outer shoulder region Wout is deeper than the maximum groove depth of thewidth direction sipe 300 in the intermediate region Wmid. Thus, a deep groove portion 320ctr is formed in the center region Wctr, and a deep groove portion 320out is formed in the outer shoulder region Wout. - Here, the shape or the like of each of the
bent portions zigzag portion 312 is similar to that in thezigzag portion 112 of thewidth direction sipe 100. Further, similar to thewidth direction sipe 100, a ratio of each of the center region Wctr and the outer shoulder region Wout to the width Ws, which is a whole width of thewidth direction sipe 300, is preferably set to fulfill the each relation represented by theformulas 1 and 2. Here, the formula 2 is replaced as below. -
0.19<(outer shoulder region Wout/width Ws)<0.25 (formula 2′) - In the present embodiment, (outer shoulder region Wout/width Ws) in the formula 2′ is 0.22. Further, in a case in which the value thereof is beyond the range of the formula 2′, the suppression effect of the uneven wear of the
shoulder land portion 30 is deteriorated. -
FIG. 5 illustrates the shape of thecircumferential direction sipe 400 formed in theshoulder land portion 40. Specifically,FIG. 5 illustrates a side shape of thecircumferential direction sipe 400 seen from a F5-F5 direction shown inFIG. 1 . As shown inFIG. 5 , thecircumferential direction sipe 400 is formed in a simply flat plate shape. - The
circumferential direction sipe 400 is provided with aside wall 410, and abottom portion 411 continued to theside wall 210. It is preferable that a groove depth of thecircumferential direction sipe 400 from thetread surface 15 to thebottom portion 411 is set in a range between the groove depth of thewidth direction sipe 100 in the intermediate region Wmid and the groove depth of thewidth direction sipe 100 in the center region Wctr or the outer shoulder land portion Wout. - Next, each size of the
width direction sipes width direction sipes circumferential direction sipes FIGS. 6(a) and 6(b) are enlarged plane views of a part of theshoulder land portion 30 and a part of theshoulder land portion 40, respectively. - As shown in
FIG. 6(a) , it is preferable that a width Wsho of theshoulder land portion 30 and the width Ws of thewidth direction sipe 100 in the tire width direction fulfill the following relation. -
0.75<(width Ws/width Wsho)≤0.885 (formula 3) - In the present embodiment, (width Ws/width Wsho) defined by the width Ws of the
width direction sipe 100 and the width Wsho of theshoulder land portion 30 is 0.818. Further, in a case in which the value thereof is beyond the range of the formula 3, the suppression effect of the uneven wear of theshoulder land portion 30 is deteriorated. - Further, it is preferable that a width Wsho of the
shoulder land portion 40 and a width Ws of thewidth direction sipe 300 in the tire width direction fulfill a similar relation. Specifically, it is preferable that the width Wsho and the width Ws fulfill the following relation. -
0.75<(width Ws/width Wsho)≤0.885 (formula 3′) - In the present embodiment, (width Ws/width Wsho) defined by the width Ws of the
width direction sipe 300 and the width Wsho of theshoulder land portion 40 is 0.869. - As shown in
FIG. 6(a) , in the present embodiment, thewidth direction sipe 100 is extended from a position of the ground contact end Se of theshoulder land portion 30 toward the inner side of the tire width direction. Similarly, as shown inFIG. 6(b) , in the present embodiment, thewidth direction sipe 300 is extended from a position of the ground contact end Se of theshoulder land portion 40 toward the inner side of the tire width direction. - Next, functions and effects of the
tire 10 described above are described. Table 1 shows a condition of a wear test of the tire 10 (examples 1 to 4) in which thewidth direction sipes -
TABLE 1 Comparative example Example 1 Example 2 Example 3 Example 4 Tire size 155/65R14 155/65R14 155/65R14 155/65R14 155/65R14 With direction sipe No Yes Yes Yes Yes Index of wear life 100 108 105 107 101 center region Wctr/width N.A. 0.47 0.34 0.48 0.53 Ws (formula 1) inner shoulder region N.A. 0.22 0.20 0.24 0.27 Win/width Ws (formula 2) and outer shoulder region Wout/ width Ws (formula 2′) width Ws/width Wsho N.A. 0.818 0.772 0.865 0.899 (outer side) (formula 3) width Ws/width Wsho N.A. 0.869 0.82 0.88 0.912 (inner side) (formula 3′) - As shown in Table 1, as an index of wear life of the tire according to the comparative example is set to 100, each index of the wear life of the tires according to the examples 1 to 4 is improved to 101 or more.
- Here, “index of wear life” denotes that a wear amount of a tread portion after an evaluation target tire travels for a predetermined distance by means of a drum test, is indexed against that of the comparative example as a reference (the wear amount is smaller as the value is larger).
- Specifically, in the drum test, an input frequency distribution in an actual use environment to the tire mounted to a front axle is reproduced. Further, after the tire travels for the predetermined distance, the tire rotation of the right tire and the left tire on the front axle is performed. Further, each wear amount is measured based on a depth of the retaining groove (including the sipe) formed in each of the shoulder land portion located at the inner side when the tire is mounted to the vehicle and the shoulder land portion located at the outer side when the tire is mounted to the vehicle.
- As shown in Table 1, in the tire according to example 4, each value thereof is beyond the each range represented by the
formulas 1, 2, 2′, 3, and 3′ (underlines are applied in Table 1). -
FIG. 7 is a view for describing a state of wear of the tires according to the comparative example and the example 1 shown in Table 1. Specifically,FIG. 7 shows a graph of each remaining amount of the groove of the shoulder land portion at the outer side, the center land portion, and the shoulder land portion at the inner side when the tire is mounted to the front axle of a vehicle (minicar). Further, as described above, after the evaluation target tire travels for the predetermined distance, the tire rotation of the right tire and the left tire is performed. - As shown in
FIG. 7 , the tire according to the example 1 has less wear difference between the shoulder land portions at the both sides and the center land portion, and therefore the shoulder land portions and the center land portion are worn uniformly. On the other hand, the tire according to the comparative example has large wear difference between the shoulder land portions at the both sides and the center land portion, and therefore the shoulder land portions are worn more quickly than the center land portion. Thus, the tire is apt to reach a use limit earlier due to the wear of the shoulder land portion in spite of the sufficient remaining amount of the groove of the center land portion. - The tire according to the example 1 has less wear difference between the shoulder land portions at the both sides and the center portion, and therefore travel distance of the tire until the use limit thereof due to the wear can be extended.
- That is, in the
tire 10 described above, thezigzag portion 112 in the center region Wctr and thezigzag portion 112 in the inner shoulder region Win of thewidth direction sipe 100 are longer than thezigzag portion 112 in the intermediate region Wmid in the tire radial direction. Thus, when the load is applied, theshoulder land portions 30 separated by thezigzag portion 112 support one another, and therefore block rigidity of the inner shoulder region Win and the center region Wctr is improved. When the block rigidity is improved, deformation of each of the inner shoulder region Win and the center region Wctr of theshoulder land portion 30 is suppressed, and therefore ground contact pressure of each of the inner shoulder region Win and the center region Wctr is decreased. - In the shoulder land portion, especially the shoulder land portion at the inner side when the tire is mounted to the vehicle, there is a tendency that each ground contact pressure of the shoulder land portions (parts adjacent to the circumferential groove) at a side of the ground contact end and a side of the center land portion becomes higher due to an influence of wheel alignment (especially, a camber angle) of the vehicle.
- Such a tendency is remarkable in the minicars or the minivans in recent years. The cause of this is that the minicars having high vehicle height by considering high comfortability and large loaded amount of cargos or the minivans generally having high vehicle height are apt to be high in the center of gravity. Thus, a roll amount of the vehicle becomes especially large in turning, and therefore a high load is applied to the shoulder land portion and the ground contact pressure becomes high.
- According to the
tire 10, as described above, each ground contact pressure of the inner shoulder region Win and the center region Wctr can be decreased and the falling of theshoulder land portion 30 can be prevented by the improvement of the block rigidity. - Therefore, the shoulder uneven wear, specifically the wear of the inner shoulder region Win and the center region Wctr proceeding more quickly than the wear of the intermediate region Wmid, is suppressed. Further, the falling of the
shoulder land portion 30 can be also prevented, and therefore heel and toe wear of theshoulder land portion 30 is also suppressed. - Further, such functions and effects are similarly obtained in the
shoulder land portion 40 at the outer side when the tire is mounted to the vehicle, although the degree of the wear is different from that of theshoulder land portion 30. - According to the present embodiment, the
width direction sipe 100 is provided with thestraight portion 111 from the tread surface of theshoulder land portion 30 to the predetermined depth of thewidth direction sipe 100. Thus, the rigidity of theshoulder land portion 30 close to thetread surface 15 is not excessively increased, and therefore the shoulder uneven wear can be suppressed while ensuring comfortability and suppressing pattern noise. - According to the present embodiment, the ratio of the
straight portion 111 to thezigzag portion 112 in the tire radial direction becomes smaller toward the ground contact end Se of theshoulder land portion 30. Thus, the rigidity of theshoulder land portion 30 becomes relatively larger toward the ground contact end Se. That is, since the ground contact pressure of theshoulder land portion 30 becomes lower toward the ground contact end Se, the uneven wear near the ground contact end Se can be suppressed effectively. - According to the present embodiment, the number of the bent portions in the intermediate region Wmid is smaller than the number of the bent portions in each of the center region Wctr and the shoulder region Win. Thus, the block rigidity of each of the inner shoulder region Win and the center region Wctr is improved much more than that of the intermediate region Wmid, and as described above, each ground contact pressure of the inner shoulder region Win and the center region Wctr is decreased. Accordingly, the shoulder uneven wear, specifically the wear of the inner shoulder region Win and the center region Wctr proceeding more quickly than the wear of the intermediate region Wmid, is suppressed.
- According to the present embodiment, the width Wsho of the
shoulder land portion 30 and the width Ws of thewidth direction sipe 100 in the tire width direction fulfill the relation of 0.75≤(width Ws/width Wsho)≤0.885. Since thezigzag portion 112 is formed in thewidth direction sipe 100 such that thezigzag portion 112 in each of the inner shoulder region Win and the center region Wctr is longer than thezigzag portion 112 in the intermediate region Wmid, and since such awidth direction sipe 100 is formed in the most part of the width of theshoulder land portion 30, the uneven wear of theshoulder land portion 30 close to the ground contact end Se and theshoulder land portion 30 close to thecenter land portion 20 can be suppressed effectively. - Further, the functions and the effects described above are similarly obtained in the
shoulder land portion 40. Further, in the present embodiment, thewidth direction sipe 100 is formed in theshoulder land portion 30 located at the inner side when the tire is mounted to the vehicle, and thewidth direction sipe 300 is formed in theshoulder land portion 40 located at the outer side when the tire is mounted to the vehicle. Thus, the uneven wear of both of the shoulder land portions can be suppressed, and therefore life of the tire determined by the wear can be extended. - As described above, the content of the present invention was disclosed through the embodiment of the present invention, however the descriptions and drawings that form a part of this disclosure are not to be considered as limitation to the present invention.
- For example, the width direction sipe 100 (300) formed in the
tire 10 may be modified as described below. -
FIGS. 8(a) and 8(b) are a plane developed view of a part of ashoulder land portion 30 including awidth direction sipe 100A according to a modified example of the present invention and a perspective view virtually illustrating a shape of thewidth direction sipe 100A, respectively. As shown inFIGS. 8(a) and 8(b) , thewidth direction sipe 100A is formed in a zigzag shape in the tire radial direction, the tire circumferential direction and the tire width direction, namely a three-dimensional sipe. Such a width direction sipe 100A and thecircumferential direction sipe 200 maybe formed in theshoulder land portion 30. - Further, as shown in
FIG. 8(b) , thewidth direction sipe 100A is formed, similar to thewidth direction sipe 100, such that a length of thewidth direction sipe 100A along the tire radial direction (depth) in each of a shoulder region and a center region is longer than a length thewidth direction sipe 100A along the tire radial direction (depth) in an intermediate region. Further, a three-dimensional sipe, which is similar to thewidth direction sipe 100A, may be formed in theshoulder land portion 40. - Further, in the embodiment described above, the width direction sipe is formed in each of the
shoulder land portion 30 and theshoulder land portion 40, however the width direction sipe may be formed in either of the shoulder land portions. Further, in the embodiment described above, a plurality of the bent portions is formed in thezigzag portion 112, however thezigzag portion 112 may be formed in a shape in which a wave-like curve is repeated, instead of a definitely bent shape as long as theshoulder portions 30 separated by thezigzag portion 112 support one another. - The entire content of Japanese Patent Application No. 2015-106562 (filed on 26 May. 2015) is incorporated in the present specification by reference.
- According to the feature of the present invention, the tire capable of suppressing shoulder uneven wear effectively even if the tire is mounted to a vehicle having high vehicle height, can be provided.
-
- 10: tire
- 15: tread surface
- 20: center land portion
- 21, 22: land portion block
- 30, 40: shoulder land portion
- 50, 60, 70: circumferential direction sipe
- 100, 100A: width direction sipe
- 111: straight portion
- 112: zigzag portion
- 112 a, 112 b, 112 c: bent portion
- 113: bottom portion
- 120ctr: deep groove portion
- 120in: deep groove portion
- 200: circumferential direction sipe
- 210: side wall
- 211: bottom portion
- 300: width direction sipe
- 311: straight portion
- 312: zigzag portion
- 312 a, 312 b, 312 c: bent portion
- 313: bottom portion
- 320ctr: deep groove portion
- 320out: deep groove portion
- 400: circumferential direction sipe
- 410: side wall
- 411: bottom portion
Claims (6)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2015-106562 | 2015-05-26 | ||
JP2015106562A JP6650216B2 (en) | 2015-05-26 | 2015-05-26 | tire |
PCT/JP2016/064409 WO2016190144A1 (en) | 2015-05-26 | 2016-05-16 | Tire |
Publications (1)
Publication Number | Publication Date |
---|---|
US20180154700A1 true US20180154700A1 (en) | 2018-06-07 |
Family
ID=57393242
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US15/575,418 Abandoned US20180154700A1 (en) | 2015-05-26 | 2016-05-16 | Tire |
Country Status (5)
Country | Link |
---|---|
US (1) | US20180154700A1 (en) |
EP (1) | EP3305558B1 (en) |
JP (1) | JP6650216B2 (en) |
CN (1) | CN107614290B (en) |
WO (1) | WO2016190144A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11338619B2 (en) | 2017-12-20 | 2022-05-24 | Bridgestone Corporation | Pneumatic tire |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000255219A (en) * | 1999-03-05 | 2000-09-19 | Bridgestone Corp | Pneumatic tire |
JP2004161166A (en) * | 2002-11-14 | 2004-06-10 | Toyo Tire & Rubber Co Ltd | Pneumatic tire |
JP2005205988A (en) * | 2004-01-21 | 2005-08-04 | Yokohama Rubber Co Ltd:The | Pneumatic radial tire |
JP2009006770A (en) * | 2007-06-26 | 2009-01-15 | Yokohama Rubber Co Ltd:The | Pneumatic tire |
US20130118663A1 (en) * | 2011-11-14 | 2013-05-16 | The Yokohama Rubber Co., Ltd. | Pneumatic Tire |
US20140166173A1 (en) * | 2011-05-11 | 2014-06-19 | Compagnie Generale Des Etablissements Michelin | Tread combining inserts and sipes |
JP2020096770A (en) * | 2018-12-19 | 2020-06-25 | 株式会社高尾 | Game machine |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4689402B2 (en) * | 2005-08-10 | 2011-05-25 | 東洋ゴム工業株式会社 | Pneumatic tire |
JP2011105135A (en) * | 2009-11-17 | 2011-06-02 | Yokohama Rubber Co Ltd:The | Pneumatic tire |
JP2013079016A (en) * | 2011-10-04 | 2013-05-02 | Yokohama Rubber Co Ltd:The | Pneumatic tire |
RU2577422C2 (en) * | 2011-11-04 | 2016-03-20 | Бриджстоун Корпорейшн | Pneumatic tire |
JP5909141B2 (en) * | 2011-11-04 | 2016-04-26 | 株式会社ブリヂストン | Pneumatic tire |
JP5956139B2 (en) * | 2011-11-11 | 2016-07-27 | 株式会社ブリヂストン | Pneumatic tire |
JP5603966B2 (en) * | 2013-03-26 | 2014-10-08 | 株式会社ブリヂストン | tire |
JP5526266B1 (en) * | 2013-06-24 | 2014-06-18 | 株式会社ブリヂストン | Pneumatic tire |
-
2015
- 2015-05-26 JP JP2015106562A patent/JP6650216B2/en active Active
-
2016
- 2016-05-16 CN CN201680029807.5A patent/CN107614290B/en active Active
- 2016-05-16 US US15/575,418 patent/US20180154700A1/en not_active Abandoned
- 2016-05-16 EP EP16799850.9A patent/EP3305558B1/en active Active
- 2016-05-16 WO PCT/JP2016/064409 patent/WO2016190144A1/en active Application Filing
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000255219A (en) * | 1999-03-05 | 2000-09-19 | Bridgestone Corp | Pneumatic tire |
JP2004161166A (en) * | 2002-11-14 | 2004-06-10 | Toyo Tire & Rubber Co Ltd | Pneumatic tire |
JP2005205988A (en) * | 2004-01-21 | 2005-08-04 | Yokohama Rubber Co Ltd:The | Pneumatic radial tire |
JP2009006770A (en) * | 2007-06-26 | 2009-01-15 | Yokohama Rubber Co Ltd:The | Pneumatic tire |
US20140166173A1 (en) * | 2011-05-11 | 2014-06-19 | Compagnie Generale Des Etablissements Michelin | Tread combining inserts and sipes |
US20130118663A1 (en) * | 2011-11-14 | 2013-05-16 | The Yokohama Rubber Co., Ltd. | Pneumatic Tire |
JP2020096770A (en) * | 2018-12-19 | 2020-06-25 | 株式会社高尾 | Game machine |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11338619B2 (en) | 2017-12-20 | 2022-05-24 | Bridgestone Corporation | Pneumatic tire |
Also Published As
Publication number | Publication date |
---|---|
CN107614290B (en) | 2020-09-22 |
EP3305558A1 (en) | 2018-04-11 |
EP3305558B1 (en) | 2019-11-13 |
EP3305558A4 (en) | 2018-06-20 |
WO2016190144A1 (en) | 2016-12-01 |
JP2016215982A (en) | 2016-12-22 |
CN107614290A (en) | 2018-01-19 |
JP6650216B2 (en) | 2020-02-19 |
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